1. Field of the Invention
The invention relates in general to electrical windings, and more specifically to new and improved methods for constructing electrical windings.
2. Description of the Prior Art
In many conventional windings, such as transformer windings, the various winding or turn layers are supported and electrically insulated from one another by cellulosic insulation, such as paper immersed in oil. Other conventional winding structures employ non-cellulosic insulating material, such as cast resin, to provide conductor support and insulation. Cellulose-free windings have certain advantages over those which use cellulose, such as being more resistant to short circuit stresses, moisture degradation, mechanical vibration, and fire, and less susceptible of out-gassing and thermal aging. Unfortunately, cellulose-free windings of conventional design also have certain disadvantages, including a relatively high cost in terms of both manufacture and loadability, and the difficulty of ridding them of shrinkage voids.
Applications Ser. No. 264,151, filed May 15, 1981, now abandoned, Ser. No. 524,227, filed Aug. 18, 1983, which is a continuation of abandoned application Ser. No. 264,151, Ser. No. 308,314, filed Oct. 2, 1981, now U.S. Pat. No. 4,403,404, Ser. No. 308,315, filed Oct. 13, 1981, now U.S. Pat. No. 4,406,056 and Ser. No. 409,681, filed Aug. 19, 1982, now abandoned, all of which are assigned to the same assignee as the present application, disclose new and improved cellulose-free winding structures, and methods of constructing such windings, which reduce the manufacturing cost and which control the formation and size of voids in the winding structure, such as those due to polymerization shrinkage. These patent applications are all based on the concept of constructing an electrical winding in a substantially continuous operation, including the steps of applying liquid resinous insulation to a substrate, quickly solidifying the liquid resin, and immediately applying one or more conductor turns to the just solidified resin.